Drug administration mechanism, method for using drug administration mechanism, and pump unit for drug administration mechanism

ABSTRACT

The present invention relates to a dosing mechanism including: a body; and a pump unit ( 3 ) that is attached to the body, in which the pump unit ( 3 ) includes: a pump ( 31 ) in which a volume of a solution feeding part therein repeats expansion and shrinkage, thereby sucking a medicine from a medicine vessel and discharging the medicine to a patient; a suction-side pipe ( 333 ) that extends from the pump ( 31 ) toward the medicine vessel; a discharge-side pipe ( 343 ) that extends from the pump ( 31 ) toward the patient; a relief pipe ( 35, 35   a ) whose one end ( 351 ) is connected to the discharge-side pipe ( 343 ) while the other end ( 352 ) is located in a part whose pressure is lower than pressure inside the discharge-side pipe when the medicine is dosed; and a relief pipe on-off valve ( 36, 36   a ) that opens and closes the relief pipe ( 35, 35   a ), a use method of a dosing mechanism, and a pump unit for a dosing mechanism.

TECHNICAL FIELD

The present invention relates to a dosing mechanism for dosing a patientwith liquid medicine filled in a medicine vessel, a use method of adosing mechanism, and a pump unit for a dosing mechanism.

BACKGROUND ART

For example, an infusion volume control apparatus is disclosed in PatentDocument 1 as a dosing mechanism for dosing a patient with liquidmedicine (medicinal solution) filled in a medicine vessel. The apparatushas a pump (micro-pump) for feeding the solution based on expansion andshrinkage of a pump chamber.

In a solution feeding system in which the apparatus disclosed in PatentDocument 1 has been installed, a backward flow can be prevented due tothe configuration of the pump even if a tube connected to the dischargeside of the pump is closed. As a result, the pump may be drivencontinuously until a large amount of the medicinal solution stays in asection between the pump and the closed site.

However, even when the tube is closed, no countermeasure is taken on theapparatus side (although Patent Document 1 describes a control unit fordetecting occurrence of an abnormal event, there is no suggestion aboutan event where the tube is closed). Therefore, when a medical workersuch as a nurse releases the closed state, the patient may be dosed in arush with the large amount of the medicinal solution which has stayed inthe tube.

BACKGROUND ART DOCUMENT Patent Document

Patent Document 1: JP-A-2011-177411

SUMMARY OF THE INVENTION Problems that the Invention is to Solve

It is therefore an object of the present invention to provide a dosingmechanism capable of suppressing a patient from being dosed with amedicinal solution in a rush as soon as closed state is released evenwhen the closing occurs in a pipe such as a tube, a use method of adosing mechanism, and a pump unit for a dosing mechanism.

Means for Solving the Problems

The present invention relates to a dosing mechanism for dosing a patientwith liquid medicine filled in a medicine vessel, including: a body; anda pump unit that is attached to the body, in which the pump unitincludes: a pump in which a volume of a solution feeding part thereinrepeats expansion and shrinkage, thereby sucking the medicine from themedicine vessel and discharging the medicine to the patient; asuction-side pipe that extends from the pump toward the medicine vessel;a discharge-side pipe that extends from the pump toward the patient; arelief pipe whose one end is connected to the discharge-side pipe whilethe other end is located in a part whose pressure is lower than pressureinside the discharge-side pipe when the medicine is dosed; and a reliefpipe on-off valve that opens and closes the relief pipe.

With this configuration, the relief pipe on-off valve is opened beforerelease of the closed state, so that an excessive amount of themedicinal solution staying in a section between the pump and the closedsite can be eliminated from a medicine channel It is therefore possibleto suppress the staying medicinal solution from flowing toward thepatient due to the release of the closed state.

Additionally, the other end of the relief pipe may be connected to thesuction-side pipe.

With this configuration, an excessive amount of the medicinal solutionstaying in the section between the pump and the closed site can bereturned to the suction-side pipe. Thus, the excessive medicinalsolution can be used effectively.

Additionally, the relief pipe on-off valve may be configured to beopened manually.

With this configuration, a medical worker can operate the relief pipeon-off valve to release the closed state after confirming the closedsite.

Additionally, the pump may be a diaphragm type pump.

With this configuration, the pump unit can be miniaturized, and thedosing mechanism can be reduced in weight. Accordingly, a burden of thepatient can be reduced when the patient is carrying the dosingmechanism.

Additionally, the present invention relates to a use method of a dosingmechanism, in which each of the above-mentioned dosing mechanisms isused, and when the discharge-side pipe is closed, the pump is suspendedto keep a state in which the medicine cannot flow toward the patient inthe discharge-side pipe, while the relief pipe on-off valve is opened.

With this configuration, an excessive amount of the medicinal solutioncan be eliminated from the medicine channel while the patient issuppressed from being dosed with the medicinal solution in a rush.

Additionally, the present invention relates to a pump unit for a dosingmechanism, including: a diaphragm type pump; pipes that are provided ona suction side and a discharge side of the pump; a relief pipe whose oneend is connected to the pipe on the discharge side while the other endis located in a part whose pressure is lower than pressure inside thepipe on the discharge side when the medicine is dosed; and a relief pipeon-off valve that opens and closes the relief pipe.

With this configuration, in the dosing mechanism in which theaforementioned pump unit has been installed, the relief pipe on-offvalve is opened before release of the closed state, so that an excessiveamount of the medicinal solution staying in a section between the pumpand the closed site can be eliminated from the medicine channel. Thus,the staying medicinal solution can be suppressed from flowing toward thepatient due to the release of the closed state.

Additionally, the other end of the relief pipe may be connected to thepipe on the suction side.

With this configuration, in the dosing mechanism in which theaforementioned pump unit has been installed, the excessive amount of themedicinal solution staying in the section between the pump and theclosed site can be returned to the suction-side pipe. Thus, theexcessive medicinal solution can be used effectively.

Advantage of the Invention

According to the present invention, the staying medicinal solution canbe suppressed from flowing toward the patient due to the release of theclosed state. Thus, it is possible to suppress a patient from beingdosed with a medicinal solution in a rush as soon as closed state isreleased even when the closing occurs in a pipe such as a tube.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing a dosing route according to anembodiment of the present invention.

FIG. 2 show a body and a disposable portion according to the presentembodiment, in which a cover portion has been removed. FIG. 2(a) is afront view,

FIG. 2(b) is a right side view, FIG. 2(c) is a longitudinal sectionalview with respect to the arrow direction A-A, and FIG. 2(d) is a backview.

FIG. 3 are schematic views showing the disposable portion (pump unit)according to the present embodiment. FIG. 3(a) is a front view, FIG.3(b) is a view showing an internal structure of the disposable portionin front view, FIG. 3(c) is a right side view, and FIG. 3(d) is a backview.

FIG. 4 are schematic views showing a flow of a medicinal solution duringdosing. FIG. 4(a) is a schematic view showing a flow of the medicinalsolution during dosing in the disposable portion according to thepresent embodiment, and FIG. 4(b) is a schematic view showing a flow ofthe medicinal solution when the closed state is released.

FIG. 5 is a schematic view showing an internal structure of a disposableportion according to another embodiment of the present invention.

FIG. 6 are schematic views showing a pump and an anti-flow valve in thedisposable portion according to the present embodiment. FIG. 6(a) is afront view, FIG. 6(b) is a plan view, and FIG. 6(c) is a longitudinalsectional view.

MODE FOR CARRYING OUT THE INVENTION

Next, the present invention will be described using an embodimentthereof. A dosing mechanism 1 according to the present embodimentincludes a body 2, and a disposable portion (a pump unit or a dosingmechanism pump unit) 3 that is removably attached to the body 2. Thedosing mechanism 1 is attached to the middle of a dosing route F from amedicine vessel F1 such as an infusion bag to a patient P, as shown inFIG. 1.

As shown in FIGS. 2(a) to 2(d), the body 2 is a part that holds thedisposable portion 3 and performs various detections, controls andmanagements. A medicine-vessel-side tube F2 and a patient-side tube F5are connected to the disposable portion 3 held by the body 2, as shownin FIG. 1. Although not shown for convenience of explanation, anopenable/closeable cover portion is provided on the front side of thebody 2. The cover portion abuts against side surfaces of a suction-sidetube 33 and a discharge-side tube 34 of the disposable portion 3 whenthe cover portion is closed. The suction-side tube 33 and thedischarge-side tube 34 will be described later. Incidentally, the upperside illustrated in FIGS. 2(a) to 2(d) corresponds to the medicinevessel F1 side (suction side) when the dosing mechanism 1 is in use, andthe lower side likewise corresponds to the patient P side (dischargeside) when the dosing mechanism 1 is in use.

The body 2 has a disposable portion mounting recess portion 22, which isa recess portion to which the disposable portion 3 can be fitted. Abody-side electric contact (not shown) is provided in a bottom surfaceof the disposable portion mounting recess portion 22. When thedisposable portion 3 is fitted to the disposable portion mounting recessportion 22, electric power for driving a pump 31 can be supplied fromthe body-side electric contact to the disposable portion 3. Above andbelow the disposable portion mounting recess portion 22 in FIGS. 2(a) to2(d), tube mounting grooves 23 are formed. The suction-side tube 33 andthe discharge-side tube 34 of the disposable portion 3 are disposed inthe tube mounting grooves 23.

The body 2 is provided with sensors that can detect a solution feedingstate of the disposable portion 3. As the sensors, pressure sensors 24and a bubble sensor 25 are provided in the present embodiment. Thepressure sensors 24 are provided at two places on the medicine vessel F1side and the patient P side of the body 2. However, only one pressuresensor may be provided at a place on the medicine vessel F1 side or thepatient P side.

The pressure sensors 24 are provided in positions corresponding to thesuction-side tube 33 and the discharge-side tube 34 in the disposableportion 3 attached to the body 2. When pressure rises in each tube, thetube is inflated to expand the diameter of the tube. When the pressurefalls in each tube, the tube shrinks to reduce the diameter of the tube.Using this phenomenon, the pressure sensors 24 detect pressure changesin the suction-side tube 33 and the discharge-side tube 34 respectivelybased on changes in diameters of the tubes 33 and 34.

Specifically, in each pressure sensor 24, as shown in FIGS. 2(a) to2(c), a movable block 241 having a groove to which the tube 33 or 34 canbe fitted is provided movably between the front side and the back side.An element 242 that can output a voltage proportional to a load appliedthereto is disposed on the back side of the movable block 241 so as toabut against the movable block 241. The tubes 33 and 34 are regulatednot to move to the front side by the cover portion (not shown) of thebody 2. Therefore, when the movable block 241 moves in accordance withexpansion/shrinkage of the tube 33 or 34, the voltage outputted from theelement 242 changes in accordance with the load applied to the element242. Thus, the pressure change in the tube 33 or 34 can be detected bythe pressure sensor 24.

Assume that the dosing route F is closed in a middle section thereof dueto bending or the like of a tube. In this case, when the dosing route Fis closed on the upstream side from the pump 31 in the disposableportion 3, the pump 31 performs suction in spite of a state where amedicinal solution (liquid medicine filled in the medicine vessel F1)hardly flows from the medicine vessel F1 side. Due to the continuousdriving of the pump 31, the internal pressure of the suction-side tube33 becomes negative. Thus, the suction-side tube 33 shrinks. On theother hand, when the dosing route F is closed on the downstream sidefrom the pump 31, the pump 31 performs discharge in spite of a statewhere the medicinal solution hardly flows to the patient P side. Due tothe continuous driving of the pump 31, the internal pressure of thedischarge-side tube 34 becomes positive. Thus, the discharge-side tube34 is inflated. In this manner, occurrence of closing can be grasped bydetection of the pressure sensors 24. Incidentally, in the disposableportion 3 according to the present embodiment, a bypass pipe 35 and abypass on-off valve 36 are provided as a relief channel for relieving anexcessive medicinal solution appearing at the time of the closing (seeFIG. 3(b)). The relief channel will be described later.

In addition, the body 2 includes a control portion 261, an internalpower supply portion 262, an external power supply input jack 263, aflow rate jack 264, and a communication jack 265. The control portion261 performs pump control of the disposable portion 3, processing andstorage of detection results of the sensors, etc. A battery is disposedin the internal power supply portion 262. A detection value of a flowrate sensor for detecting a dropping amount or the like is inputted tothe flow rate jack 264. The flow rate sensor is attached to a not-showndrip cylinder located on the patient P side from the medicine vessel F1.The communication jack 265 serves to output dosing history data, sensordetection results, etc. In addition, though not shown, the body 2 alsoincludes a speaker for outputting an alarm sound or the like, an LEDlamp for indicating an alarm or the like, a sensor for detecting thatthe cover portion has been opened, and a liquid crystal display portionfor displaying various pieces of information. In addition, the body 2may include a part to which a band or the like for attaching the body 2to a body of the patient P can be attached, or a part which can beattached to an infusion stand or the like for use in a medicalinstitution.

As shown in FIGS. 3(a) to 3(d), the disposable portion 3 includes thepump 31, a free flow preventing valve 32, the suction-side tube(suction-side pipe) 33, the discharge-side tube (discharge-side pipe)34, the bypass pipe (relief pipe) 35, and the bypass on-off valve(relief pipe on-off valve) 36. The pump 31, the free flow preventingvalve 32, the bypass pipe 35 and the bypass on-off valve 36 are receivedintegrally in a casing 37. Therefore, the disposable portion 3 can beattached to the body 2 and removed therefrom easily. The suction-sidetube 33 and the discharge-side tube 34 are inserted to tube connectionpipes 332 and 342 protruding from the casing 37. Connectors 331 and 341which can be connected to the tubes F2 and F5 extending from themedicine vessel F1 and the patient P are provided at front ends of thesuction-side tube 33 and the discharge-side tube 34. The tube connectionpipes 332 and 342 protrude eccentrically to the front side from a flatsurface and a bottom surface of the casing as shown in FIG. 3(c).Therefore, if the front side and the back side of the casing 37 areconfused with each other when the disposable portion 3 is attached tothe body 2, the tube connection pipes 332 and 342 are caught in the tubemounting grooves 23 of the body 2 so that the disposable portion 3cannot be attached. It is therefore possible to prevent the disposableportion 3 from being erroneously attached to the body 2.

Incidentally, according to another embodiment, the outer shape of thepart of the body 2 to which the disposable portion 3 can be attached maybe formed into an asymmetrical shape, or concave portions or convexportions may be formed in asymmetric positions. In this manner, it ispossible to prevent the disposable portion 3 from being erroneouslyattached to the body 2. Further, marking display (arrow display) may beprovided in the disposable portion 3 so that erroneous attachment of thedisposable portion 3 to the body 2 can be suppressed.

A disposable-portion-side electric contact 38 which can be connected toa body-side electric contact (not shown) is formed in the back surfaceof the casing 37. Accordingly, when the back surface of the casing 37 isaligned with the bottom surface of the disposable portion mountingrecess portion 22 of the body 2 to establish electric connection betweenthe body-side electric contact and the disposable-portion-side electriccontact 38, electric conduction to the pump 31 can be established todrive the pump 31.

The pump 31 can suck medicine from the medicine vessel F1 and dischargethe medicine to the patient P. As for the type of the pump, for example,a piston pump, a roller pump and a diaphragm type pump can be used.However, the diaphragm type pump is preferred because it does notrequire a motor. In the present embodiment, therefore, the diaphragmtype pump is used. When the diaphragm type pump is used as the pump 31,the pump can be miniaturized because it does not require a motor. Thus,the disposable portion 3 can be also miniaturized, and the weight of thedosing mechanism 1 can be reduced. Accordingly, a burden of the patientP can be reduced when the patient P is carrying the dosing mechanism 1.Particularly there is a large merit for the patient P who has to bealways dosed with medicine. In addition, the discharge amount of themedicinal solution can be controlled with high accuracy by the diaphragmtype pump.

A pump using MEMS technology relating to an integrated device is used asthe pump 31 according to the present embodiment. For example, amicro-pump disclosed in JP-A-2013-117211 is used. In the pump 31, asshown in FIG. 6(c), a diaphragm 314 made of a stainless steel thin plateis vibrated by a piezoelectric element so that the volume of a pumpchamber 315 serving as a part for feeding the solution can repeatexpansion and shrinkage. A valve 316 allowing the medicinal solution toflow only in the suction direction is provided on the suction side inthe pump chamber 315, and a valve 317 allowing the medicinal solution toflow only in the discharge direction is provided on the discharge side.Due to the valves, the solution is fed from a suction-side channel 311to a discharge-side channel 312.

Incidentally, a required volume of the pump 31 differs depending on anamount of the medicinal solution to be dosed. Therefore, a mark forspecifying the volume may be indicated in the casing 37, or the shape ofthe casing 37 may be changed.

In addition, control contents of the pump 31 in the body 2 (controlportion 261) differ depending on the volume of the pump 31. Therefore,when the mark indicated in the casing 37 or the shape of the casing 37is changed in accordance with the volume of the pump 31 as describedabove, the body 2 may be configured to recognize the mark or the casingshape and to automatically change the control contents in accordancewith the recognition. Further, an identifier such as an IC chip may beprovided in the casing 37, and a unit for reading the identifier may beprovided in the body 2. With this configuration, the control contentscan be automatically changed only when the disposable portion 3 isattached to the body 2. Incidentally, when the identifier is provided asdescribed above, a use history of the disposable portion 3 may berecorded in the identifier so that the disposable portion 3 removedafter use cannot be used again.

The free flow preventing valve 32 is provided for preventing occurrenceof an unintended flow passing through the pump 31 due to pressure of themedicinal solution caused by gravitation when the pump 31 is not beingdriven. As shown in FIG. 6(c), the free flow preventing valve 32according to the present embodiment is connected to the discharge-sidechannel 312 and a balance channel 313 of the pump 31 so that the freeflow preventing valve 32 can be integrated with the pump 31.Incidentally, as shown in FIG. 6(b), the width of the free flowpreventing valve 32 is formed to be smaller than the width of the pump31. Thus, there is a step between the both. As shown in FIG. 6(a), thereis a positional deviation between a protruding part of the pump 31 wherethe suction-side channel 311 passes and a protruding part of the freeflow preventing valve 32 where an exit-side main channel 322 passes. Dueto the aforementioned step and the aforementioned positional deviationbetween the two protruding parts, the pump 31 and the free flowpreventing valves 32 can be suppressed from being attached to the casing37 on the wrong way around. Thus, the disposable portion 3 can beassembled efficiently.

In the free flow preventing valve 32, as shown in FIG. 6(c), anentrance-side main channel 321 (which is connected to the discharge-sidechannel 312 of the pump 31) and the exit-side main channel 322 areprovided on one surface side of a diaphragm 324, and a balance channel323 (which is connected to the balance channel 313 of the pump 31) isformed on the other surface side. In this configuration, a flow betweenthe entrance-side main channel 321 and the exit-side main channel 322occurs only when the diaphragm 324 moves. That is, when only thepressure of the medicinal solution from the medicine vessel F1 isapplied onto the diaphragm 324, the pressure in the entrance-side mainchannel 321 and the pressure in the balance channel 323 are balanced.Thus, the diaphragm 324 stands still not to generate any flow in thefree flow preventing valve 32. On the other hand, when the pump 31 isbeing driven, the pressure of the medicinal solution pushed out by thepump 31 is larger than the internal pressure of the balance channel 323.Thus, a flow from the entrance-side main channel 321 to the exit-sidemain channel 322 is generated. Due to the free flow preventing valve 32thus provided, a flow of the medicinal solution can be generated in thedisposable portion 3 only when the pump 31 is being driven. It istherefore possible to prevent the patient P from being unintentionallydosed with the medicinal solution.

The suction-side tube 33 is a tube extending from the pump 31 toward themedicine vessel F1. The discharge-side tube 34 is a tube extending fromthe pump 31 toward the patient P. The tubes 33 and 34 are formed of softresin such as silicone rubber. As will be described later, changes indiameters of the tubes 33 and 34 are detected by the pressure sensors24. Therefore, regarding the tubes 33 and 34, at least the parts to bedisposed in the pressure sensors 24 have to be formed withinpredetermined error ranges as to their materials (such as resincompositions, densities, etc.), tube thicknesses, and tube diameters.Incidentally, according to another embodiment, in which changes inpressure are not detected using any piping, not soft tubes but hardpipes may be used in the disposable portion 3.

The connectors 331 and 341 are provided at the front ends of the tubes33 and 34 respectively. The connectors 331 and 341 are general-purposearticles made of hard resin. As shown in FIG. 1, the connectors 331 and341 are connected to the medicine-vessel-side tube F2 and thepatient-side tube F5 (respectively including connectors F3 and F4 whoseshapes have male-female relations to the connectors 331 and 341 of thedisposable portion 3 so that the connectors F3 and F4 can be connectedto the connectors 331 and 341), for example, by screwing. Due to theconnectors 331 and 341, the disposable portion 3 and themedicine-vessel-side tube F2 can be separated from each other, and thedisposable portion 3 and the patient-side tube F5 can be separated fromeach other. Thus, distances of the medicine vessel F1 and the patient Pfrom the dosing mechanism 1 can be set desirably. Accordingly, the tubesF2 and F5 are hardly impeditive when the patient P is carrying thedosing mechanism 1.

Incidentally, the connector 331 or 341 may be disposed at a front end ofat least one of the suction-side tube 33 and the discharge-side tube 34.When a connector is provided on only one side, the disposable portion 3includes up to the medicine vessel F1 (or a not-shown drip cylinder,which is disposed on the patient P side from the medicine vessel F1) onthe side where no connector is provided. On the opposite side withrespect to the dosing mechanism 1, the disposable portion 3 includes upto a needle F6 to be inserted into the patient P.

The bypass pipe 35 connects the suction-side tube 33 and thedischarge-side tube 34 to each other without interposing the pump 31therebetween. As shown in FIG. 3(b), the bypass pipe 35 branches from asuction-side pipe 333 and a discharge-side pipe 343 inside the casing 37(in the present embodiment, the bypass pipe 35 branches from the bypasson-off valve 36 located in an end portion of the discharge-side pipe343).

At the time of dosing, as shown by the arrow in FIG. 4(a), the medicinalsolution entering the casing 37 from the tube connection pipe 332 passesthrough the suction-side pipe 333 in the casing 37, the pump 31, thefree flow preventing valve 32, the bypass on-off valve 36, and thedischarge-side pipe 343 in the casing 37, sequentially. The medicinalsolution is then discharged from the tube connection pipe 342 in thecasing 37. Incidentally, in the bypass on-off valve 36, a channelthrough which the medicinal solution can pass without stopping is formedin parallel with a channel which can be opened and closed by the bypasson-off valve 36. At a normal operation (except when the bypass on-offvalve 36 is operated to be open), the medicinal solution passes throughthe channel through which the medicinal solution can pass withoutstopping.

On the other hand, when the dosing route F is closed and the bypasson-off valve 36 is opened, as shown by the arrow in FIG. 4(b), of themedicinal solution staying in the discharge-side tube 34, an excessiveamount passes through the tube connection pipe 342 in the casing 37, thedischarge-side pipe 343 in the casing 37, the bypass on-off valve 36 (ofthe bypass on-off valve 36, the channel which can be opened and closed),the bypass pipe 35, and the suction-side pipe 333 in the casing 37,sequentially. Then the medicinal solution is discharged from the tubeconnection pipe 332 in the casing 37.

Due to the existence of the bypass pipe 35 thus configured, when thebypass on-off valve 36 is open, the suction-side tube 33 and thedischarge-side tube 34 are made to communicate with each other, so thatan excessive amount of the medicinal solution can be returned to thesuction-side tube 33 if the dosing route F is closed.

In the present embodiment, as shown in FIG. 3(b), one end 351 of therelief pipe (the bypass pipe 35 in the present embodiment) is connectedto the suction-side pipe 333, and the other end 352 is connected thedischarge-side pipe 343 through the bypass on-off valve 36. However, thepresent invention is not limited to such a configuration. For example,the present invention may have a configuration as shown in FIG. 5. In arelief pipe 35 a shown in FIG. 5, one end 351 is opened to air while theother end 352 is connected to the discharge-side pipe 343 through arelief pipe on-off valve 36 a corresponding to the bypass on-off valve36. The opened part is covered with a vessel B. In this manner, an endportion (the one end 351 in the example shown in FIG. 5) of the reliefpipe 35 a can be disposed in a part whose pressure is lower than thepressure inside the discharge-side pipe when medicine is being dosed. Inaddition, in the example shown in FIG. 5, the vessel B is provided forrecovering an excessive amount of the medicinal solution leaking fromthe one end 351 of the relief pipe 35 a when the bypass on-off valve 36is open. However, an absorber may be instead disposed for absorbing theleaking excessive amount of the medicinal solution. Incidentally, in theexample of FIG. 5, it is necessary to provide a check valve or the liketo prevent the air from entering the discharge-side pipe 343 from theone end 351 of the relief pipe 35 a. In the example of FIG. 5, therelief pipe on-off valve 36 a corresponding to the bypass on-off valve36 is located at the other end 352 of the relief pipe 35 a. However, theposition of the relief pipe on-off valve 36 a is not limited. Forexample, the relief pipe on-off valve 36 a may be disposed at the oneend 351 or between the two ends.

When a pump in which the volume of a solution feeding part (the pumpchamber 315 shown in FIG. 6(c)) repeats expansion and shrinkage, such asa diaphragm type pump, is used as the pump 31, a backward flow passingthrough the pump 31 can be prevented due to the configuration of thepump 31 even if the tube 34 or F5 connected to the discharge side of thedisposable portion 3 is closed. As a result, the pump 31 may be drivencontinuously until a large amount of the medicinal solution stays in asection between the pump 31 and the closed site. Of the medicinalsolution staying in the section between the pump 31 and the closed site,an excessive amount is returned to the suction side from the pump 31. Onthis occasion, the excessive medicinal solution is passed through thebypass pipe 35 and the bypass on-off valve 36.

As shown in FIG. 3(b), the bypass on-off valve 36 is provided in an endportion of the bypass pipe 35 so that the bypass on-off valve 36 canopen and close the channel of the bypass pipe 35. The bypass on-offvalve 36 is configured to be opened manually. A medical worker or thepatient P can push a button 361 shown in FIG. 3(a) to thereby open thebypass on-off valve 36. When the medical worker or the patient Preleases his/her finger from the button 361, the bypass on-off valve 36is automatically closed by a spring or the like. The reason why thebypass on-off valve 36 is not automatically closed is because themedical worker or the patient P should confirm the closed site andinvestigate a cause of the closing when the dosing route F is closed inits middle. Thus, proper countermeasures can be taken when the dosingroute F has been closed. In some estimated situation, the bypass on-offvalve 36 that can be automatically opened when the pressure of thebypass pipe 35 or the like is beyond a predetermined pressure may beused.

The disposable portion 3 according to the present embodiment is madedisposable. Therefore, the dosing mechanism 1 can be used sanitarily andsafely. Although depending on the kind of medicine or the use state, thedisposable portion 3 is replaced typically when it is used for aboutthree days, or in a longest case when it is used for about thirty days.When the disposable portion 3 is made disposable, it is not necessary toperform inspection of discharge accuracy, which should be performed by amedical engineer (ME) in a medical institution. Accordingly, the dosingmechanism 1 can be managed easily in the medical institution. In thefuture, the dosing mechanism 1 may be able to be managed by a nurse orthe like in each ward without using power of any medical engineer.

In addition, if, of the suction-side tube 33 and the discharge-side tube34, at least the parts corresponding to the pressure sensors 24 aremanaged as to their materials, dimensional errors, etc., each of thetubes located correspondingly to the pressure sensors 24 can be arrangedsubstantially with the same diameter or the same hardness (ease ofchanging in diameter) even when the disposable portion 3 is replaced.Accordingly, the tube can be prevented from varying in diameter orhardness as in a case where each tube prepared by a medical institutionis connected to the dosing mechanism. It is therefore possible to surelydetect a change in pressure.

Next, a method for using the dosing mechanism 1 will be describedbriefly. First, the tube F2 extending from the medicine vessel F1 andthe tube F5 extending from the patient P side (the needle F6 is attachedto the tube F5 in advance when the tube 5 is not provided with theneedle F6) are connected to the disposable portion 3. Then thedisposable portion 3 to which the tube F2 and the tube F5 have beenconnected is connected to the body 2. On this occasion, the disposableportion 3 is in the state shown in FIG. 1. If necessary, a drip cylinderor a flow rate sensor may be attached. Next, bubbles are purged from thedosing route F. The needle F6 is then inserted into the patient P. Next,driving the pump 31 is started. As a result, the medicinal solution issent into the body of the patient P by the pump 31.

When the dosing route F is closed (particularly closed in a section ofthe dosing route F on the patient P side from the pump 31), the pressuresensors 24 detect the closing, and the control portion 261 issuesnotification of an alarm (notification using an alarm sound or lightingan alarm lamp). In response thereto, a medical worker or the patient Psuspends the pump 31 (the pump 31 may be automatically suspendedinterlocking with the notification of the alarm). In addition, themedical worker or the patient P closes an on-off valve (not shown) in acase where the on-off valve is provided on the patient P side from thebody 2. Then, the medical worker or the patient P opens the bypasson-off valve 36 of the disposable portion 3. After that, the medicalworker or the patient P confirms the closed site and releases the closedstate (for example, extends a tube which has been bent, in order tosecure a flow channel). In this manner, the bypass on-off valve 36 isopened before release of the closed state, so that an excessive amountof the medicinal solution staying in a section between the pump 31 andthe closed site can be returned to a section of the dosing route F onthe medicine vessel F1 side from the pump 31. In safety, the stayingmedicinal solution can be suppressed from flowing toward the patient Pdue to the release of the closed state. In addition, the medicinalsolution returned to the section on the medicine vessel F1 side is dosedto the patient P again by the pump 31. Thus, the excessive medicinalsolution caused by the occurrence of the closing can be usedeffectively. After the release of the closed state, the on-off valve isopened in a case where the on-off valve is provided on the patient Pside. Thus, driving of the pump 31 is resumed to resume dosing themedicinal solution.

The present application is based on Japanese Patent Application No.2014-240045 filed on Nov. 27, 2014, the contents of which areincorporated herein by reference.

The embodiment of the present invention has been described above.However, the present invention is not limited to the embodiment. Variouschanges may be made on the present invention without departing from thegist of the invention.

DESCRIPTION OF REFERENCE NUMERALS AND SIGNS

1 dosing mechanism

2 body

24 pressure sensor

3 disposable portion, pump unit (dosing mechanism pump unit)

31 pump

315 solution feeding part, pump chamber

33 suction-side pipe, suction-side tube

331 connector (suction side)

34 discharge-side pipe, discharge-side tube

341 connector (discharge side)

35 relief pipe, bypass pipe

351 one end of relief pipe (bypass pipe)

352 the other end of relief pipe (bypass pipe)

36 bypass on-off valve (relief pipe on-off valve)

F1 medicine vessel

P patient

1. A dosing mechanism for dosing a patient with liquid medicine filledin a medicine vessel, comprising: a body; and a pump unit that isattached to the body, wherein the pump unit comprises: a pump in which avolume of a solution feeding part therein repeats expansion andshrinkage, thereby sucking the medicine from the medicine vessel anddischarging the medicine to the patient; a suction-side pipe thatextends from the pump toward the medicine vessel; a discharge-side pipethat extends from the pump toward the patient; a relief pipe whose oneend is connected to the discharge-side pipe while the other end islocated in a part whose pressure is lower than pressure inside thedischarge-side pipe when the medicine is dosed; and a relief pipe on-offvalve that opens and closes the relief pipe.
 2. The dosing mechanismaccording to claim 1, wherein the other end of the relief pipe isconnected to the suction-side pipe.
 3. The dosing mechanism according toclaim 1, wherein the relief pipe on-off valve is configured to be openedmanually.
 4. The dosing mechanism according to claim 1, wherein the pumpis a diaphragm type pump.
 5. A use method of a dosing mechanism, whereinthe dosing mechanism according to claim 1 is used, and when thedischarge-side pipe is closed, the pump is suspended to keep a state inwhich the medicine cannot flow toward the patient in the discharge-sidepipe, while the relief pipe on-off valve is opened.
 6. A pump unit for adosing mechanism, comprising: a diaphragm type pump; pipes that areprovided on a suction side and a discharge side of the pump; a reliefpipe whose one end is connected to the pipe on the discharge side whilethe other end is located in a part whose pressure is lower than pressureinside the pipe on the discharge side when the medicine is dosed; and arelief pipe on-off valve that opens and closes the relief pipe.
 7. Thepump unit for a dosing mechanism according to claim 6, wherein the otherend of the relief pipe is connected to the pipe on the suction side.